Nanostructured material sensor processing using microfabrication techniques

Abstract

Purpose -The development of chemical sensors based on nanostructures, such as nanotubes or nanowires, depends on the capability to reproducibly control the processing of the sensor. Alignment and consistent electrical contact of nanostructures on a microsensor platform is challenging. This can be accomplished using labor-intensive approaches, specialized processing technology, or growth of nanostructures in situ. However, the use of standard microfabrication techniques for fabricating nanostructured microsensors is problematic. The purpose of this paper is to address this challenge using standard photoresist processing combined with dielectrophoresis. Design/methodology/approach -Nanostructures are suspended in photoresist and aligned between opposing sawtooth electrode patterns using an alternating current (AC) electric field (dielectrophoresis). The use of photoresist processing techniques allow the burying of the nanostructures between layers of metal, thus improving the electrical contact of the nanostructures to the microsensor platform.Findings -This approach is demonstrated for both multi-walled carbon nanotubes and tin oxide nanowires. Preliminary data show the electrical continuity of the sensor structure as well as the response to various gases. Research limitations/implications -It is concluded that this approach demonstrates a foundation for a new tool for the fabrication of microsensors using nanostructures, and can be expanded towards enabling the combination of common microfabrication techniques with nanostructured sensor development. Originality/value -This approach is intended to address the significant barriers of deposition control, contact robustness, and simplified processing to realizing the potential of nanotechnology as applied to sensors.

A novel methane sensor based on porous SnO2nanorods: room temperature to high temperature detection

“…Furthermore, this sensor has two major unique and novel attributes. First is the use of microfabrication processes to fabricate microsized sensor electrodes [17]. The application of photolithography and sputtering processing to fabricate sensor electrodes enables the sensor to have small sizes.…”

“…SnO 2 nanobelts were used for comparison with the porous SnO 2 nanorods as a sensing material. The synthesis of the SnO 2 nanobelts is described elsewhere [17]. Briefly, the nanobelts were synthesized by a thermal evaporation-condensation (TEC) approach beginning with evaporating SnO from an alumina growth boat.…”

“…In our case, this has been overcome by fabricating the sensors using standard microfabrication techniques combined with the alignment of the nanostructures using dielectrophoresis (DEP). Details have been published elsewhere [17]. Briefly, alumina substrates were patterned with a sawtooth electrode pattern with contact pads through photolithography and 2500 Å of platinum was deposited by sputter deposition.…”